1. Field of the Invention
The present invention relates to a tool with an internal fluid passage, which is mounted on a machine tool and used to machine a workpiece on the machine tool.
2. Description of the Related Art
Published patent application P2005-532917 (International publication WO2003/097283) discloses a milling tool having a chip outlet passage made therein for discharging, together with air, chips produced when a workpiece is machined by the milling tool.
The milling tool has a gap in a milling head (cutting blade) on its tip end. The chips are produced when the workpiece is machined by the milling tool. The chips are drawn through the gap into the chip outlet passage and are discharged from the chip outlet passage.
If the milling tool disclosed in P2005-532917 has a large tool diameter, then the gap is also of a large size, and hence the amount of air which is drawn through the gap is large. As a result, air flows at a high speed in the chip outlet passage. Air draws the chips therewith into the chip outlet passage and discharges the chips well through the chip outlet passage.
If the milling tool has a small tool diameter, then since the gap has a correspondingly small cross-sectional area, the amount of air flowing through the gap is low and hence air flows at a low speed in the chip outlet passage, so that attractive forces for drawing in the chips are reduced. As a result, the chips drawn together with air from the gap tend to be progressively deposited in the chip outlet passage. The deposited chips may not easily be cleared from the chip outlet passage.